/Engine/Plugins/Importers/USDImporter/Source/USDStageEditor/Public/USDStageEditorBlueprintLibrary.h
Exports the currently opened USD Stage to a single "flattened" USD layer. Corresponds to the "File -> Export -> All Layers" action on the USD Stage Editor menu bar.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="USD|Menu Actions") static void FileExportFlattenedStage ( const [FString](API\Runtime\Core\Containers\FString) & OutputLayer )